Research is proposed in "Personality, Experimental Social Psychology, and Health Interventions" in which we examine individual differences in affective reactivity and deliberative ability thought to be associated with the effectiveness of a behavioral intervention, specifically a decision aid. Although many important decisions made by older adults (e.g., choosing a medical procedure) involve thoughts and feelings about decision options, relatively little is known about how affective feelings and deliberation interact in such judgment and decision processes. Human decision making is a complex phenomena involving multiple components that may change with age. We suggest that deliberative processing may show weaker effects on the judgments and decisions of older (vs. younger) adults while affective processes may have a stronger influence. As a result, older adults may produce different decisions than younger adults. In some cases older adults' decisions may appear better; in other cases they may appear worse. In the present proposal we build on recent findings about the role of affect and deliberation in the decision processes of older and younger adults. Recent evidence suggests that affect (and affective personality) may be critical to making complex choices. We propose to examine whether older (vs. younger) adults will make better choices among complex and uncertain options due to an hypothesized increase in the salience of affect among older adults. In addition, although "thinking hard" is often considered the hallmark of good decision making, a behavioral intervention requiring increased deliberation is predicted to disrupt rather than enhance performance. The disruption is expected to be greater for older than younger adults due to age-related inefficiencies in deliberative processing. This research will add to the growing body of knowledge concerning how affective and deliberative personality traits and ways of thinking may interact and follow particular developmental paths. It will also examine the impact of a common decision aiding technique (thinking harder about future likely events) on the decision processes of older versus younger adults in a task thought to be affect-based. Understanding the process that underlie the judgements and decisions of older adults can help us identify areas in which they may be most vulnerable and guide efforts to help them maintain their health, financial security, and quality of life.